Integrated cardiac rhythm management system with heart valve

ABSTRACT

Systems and methods using a heart valve and an implantable medical device, such as for event detection and optimization of cardiac output. The cardiac management system includes a heart valve, having a physiological sensor. The physiological sensor is adapted to measure at least one of an intrinsic electrical cardiac parameter, a hemodynamic parameter or the like. The system further includes an implantable electronics unit, such as a cardiac rhythm management unit, coupled to the physiological sensor of the heart valve to receive physiological information. The electronics unit is adapted to use the received physiological information to control delivery of an electrical output to the subject.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.11/466,974, filed on Aug. 24, 2006, which is herein incorporated byreference.

TECHNICAL FIELD

Event detection and therapy with biomedical devices and in particularevent detection and therapy using sensors coupled with a heart valve.

BACKGROUND

The body includes a plurality of organs and systems that performfunctions necessary for maintaining the health of a person. Thecirculatory system is one example of a system that includes the heartorgan as its centerpiece. Other body systems include the respiratorysystem, digestive system, endocrine system, nervous system or the like.The organs of these systems provide a variety of physiologicalparameters useful for observing the normal and abnormal behaviors of thebody. Observation of these parameters and recognition of potentialnormal and abnormal events through observation allows effectivediagnosis or treatment of diseases, conditions or the like. Thecomplexity of the various systems of the body provide multipleparameters that, when observed, provide insight regarding the onset of acondition or disease. Measuring each of these parameters and correctlyidentifying when measurements indicate a condition is difficult.Identifying a condition becomes even more difficult when somemeasurements indicate the onset or existence of a condition or diseasewhile others do not.

One example of a body system is the circulatory system. The heart is thecentral organ for the circulatory system and includes anelectromechanical system performing two major pumping functions. Theleft portions of the heart draw oxygenated blood from the lungs and pumpit to the organs of the body to provide the organs with oxygen. Theright portions of the heart draw deoxygenated blood from the organs andpump it into the lungs where the blood is oxygenated. The pumpingfunctions are accomplished by contractions of the heart. An increase inthe body's metabolic need for oxygen is satisfied primarily by a higherfrequency of the contractions, i.e., a higher heart rate, along withchanges in stroke volume.

Measurements of the various electrical and mechanical functions of theheart provide a variety of physiological parameters that can indicatethe onset of a condition, for instance, heart failure, arrhythmia(fibrillation, tachycardia, bradycardia), ischemia, or the like. Thesephysiological parameters include, for example, electrocardiaccharacteristics, heart sounds (e.g., S3 amplitude), DC impedance nearthe lungs, heart rate, respiration rate, weight, intracardiac pressure,blood flow, blood velocity, temperature, chemical presence andconcentration or the like. At least some of these parameters mayindicate the onset or change of a condition and thereby provide an alertthat therapy or therapy adjustment is needed, such as defibrillation,change in pacing schema or the like. It is difficult, however, todetermine when an event is beginning when only some measurements forthese parameters indicate the onset of a condition.

In some examples, clinicians set measured parameter thresholds inimplantable medical devices, such as pacemakers, defibrillators, cardiacresynchronization devices, or the like. Many clinicians adopt aconservative approach geared toward applying therapy even when therapymay not be needed.

Therapy is thereby provided when at least one or more of themeasurements for a parameter are above the set threshold—even when themeasurements for other parameters indicate there is not an event. Falsepositives, non-events that include measurements above at least somethresholds, thereby initiate treatment. In some circumstances, such asdefibrillation shock therapy, the user of the implantable medical devicereceives painful and unnecessary treatment in response to such a falsepositive. The issues described above, with regard to cardiac therapy,such as setting conservative thresholds or the like, extend to othermedical devices associated with the other organs and systems of thebody.

Further, information about when many conditions begin may involve theleft ventricle or left atrium. It is difficult to position sensorswithin the left side of the heart. The ability to precisely measurephysiological parameters of the left side of the heart is therebylimited. Further still, because of the convoluted vasculature it isdifficult to position electrodes for defibrillation and pacing therapywithin the left side of the heart.

The present inventors have recognized that event detection systems andmethods that address the above issues are needed. The present inventorshave also recognized that what is further needed are implantable eventdetection systems capable of sensing multiple physiological parametersand providing increased specificity for delivery of therapy, such as indifficult to reach locations of the heart.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic diagram showing one example of a cardiacmanagement system including a replacement tricuspid heart valve.

FIG. 1B is a schematic diagram showing one example of a cardiacmanagement system including a replacement mitral heart valve.

FIG. 1C is a schematic diagram showing one example of a cardiacmanagement system including a replacement aortic heart valve.

FIG. 1D is a schematic diagram showing one example of a cardiacmanagement system including a replacement pulmonic heart valve.

FIG. 2 is a schematic diagram showing one example of a cardiacmanagement system with a heart valve.

FIG. 3 is a perspective view of one example of a heart valve with asensor for measuring at least a hemodynamic parameter.

FIG. 4A is a perspective view of another example of a heart valve with asensor for measuring at least a hemodynamic parameter.

FIG. 4B is a perspective view of another example of a heart valve with asensor for measuring at least a hemodynamic parameter.

FIG. 5 is a top view of yet another example of a heart valve with asensor for measuring at least a hemodynamic parameter.

FIG. 6A is a top view of still another example of a heart valve with asensor for measuring at least a hemodynamic parameter.

FIG. 6B is a cross-sectional view of the heart valve of FIG. 6A, takenalong the section line 6B-6B.

FIG. 7 is a perspective view of a further example of a heart valve witha sensor for measuring at least a hemodynamic parameter.

FIG. 8 is a perspective view of an additional example of a heart valvewith a sensor for measuring at least a hemodynamic parameter.

FIG. 9 is a perspective view of an additional example of a heart valvewith a sensor for measuring at least a hemodynamic parameter.

FIG. 10A is a perspective view of an example of a heart valve includingan opened and closed valve indicating circuit.

FIG. 10B is a perspective view of an example of a double leaflet heartvalve including an opened and closed valve indicating circuit.

FIG. 11 is a schematic diagram of one example of a heart valve with acircuit that harvests energy and detects one or more physiologicalparameters.

FIG. 12 is a block diagram showing one example of an event detectionmethod.

FIG. 13 is a block diagram showing one example of an event detectionmethod.

FIG. 14 is a block diagram showing one example of a cardiacresynchronization method.

DETAILED DESCRIPTION

The following detailed description includes references to theaccompanying drawings, which form a part of the detailed description.The drawings show, by way of illustration, specific embodiments in whichthe invention may be practiced. These embodiments, which are alsoreferred to herein as “examples,” are described in enough detail toenable those skilled in the art to practice the invention. Theembodiments may be combined, other embodiments may be utilized, orstructural, logical and electrical changes may be made without departingfrom the scope of the present invention. The following detaileddescription is, therefore, not to be taken in a limiting sense, and thescope of the present invention is defined by the appended claims andtheir equivalents.

In this document, the terms “a” or “an” are used, as is common in patentdocuments, to include one or more than one. In this document, the term“or” is used to refer to a nonexclusive or, unless otherwise indicated.Furthermore, all publications, patents, and patent documents referred toin this document are incorporated by reference herein in their entirety,as though individually incorporated by reference. In the event ofinconsistent usages between this document and those documents soincorporated by reference, the usage in the incorporated reference(s)should be considered supplementary to that of this document; forirreconcilable inconsistencies, the usage in this document controls.

FIGS. 1A, B are schematic diagrams showing examples of portions of acardiac management system 100 including an implantable medical device102, a lead system 104, an external system 106, and a wireless telemetrylink 108. In one example, the implantable medical device 102 includes acardiac function management device, such as a cardiac pacer,defibrillator, cardioverter, cardiac resynchronization devices,combinations of any two or more of the above, or the like for permanentor semi-permanent implantation. In another example, the external system106 includes a wireless server system, such as the LATITUDE® system, aregistered trademark of Cardiac Pacemakers, Inc. of St. Paul, Minn.

As shown in the examples of FIGS. 1A, B, the lead system 104 is coupledwith a replacement heart valve 110. Optionally, the lead system 104couples with the heart valve through the atrium 112 of the heart 111similarly to some sensing and therapy leads. In another option, shown inFIG. 1A, the lead system 104 includes electrodes 105, such as pacingand/or defibrillation electrodes, operable to provide therapy to theheart at a variety of locations along the lead system 104. In yetanother option, shown in FIG. 1B, the lead system 104 is coupled withthe valve 110 extravascularly, for instance through the myocardium.

In FIG. 1A, the replacement valve 110 is shown between the right atrium112 and the right ventricle 114 in place of the tricuspid valve. In FIG.1B, the replacement valve 110 is shown between left atrium 116 and theleft ventricle 118 in place of the mitral valve. The heart valve 110includes one or more sensors, including, but not limited to at least oneof a hemodynamic sensor (e.g., valve deflection sensors, blood flowsensors, chemical sensors, temperature sensors, pressure sensors or thelike) and one or more electrodes for cardiac sensing, pacing,defibrillation or the like, further described below. The sensorscommunicate with the implantable medical device 102 and provideinformation used by the implantable medical device 102, such as to applyand change, for instance, pacing therapy, defibrillation therapy, drugdispensing or the like.

FIGS. 1C, D are schematic diagrams showing another example of the heartvalve 110. In FIG. 1C, the heart valve 110 is placed within the aorta120 and replaces the aortic valve. In FIG. 1D, the heart valve is placedwithin the pulmonary artery 122 and replaces the pulmonic valve. Asshown, in the examples of FIGS. 1C, D, the heart valve 110 is wirelesslycoupled with the implantable medical device 102 through the use of atransceiver 124 (e.g., a transmitter, receiver, transmitter/receiver, orthe like). The implantable medical device 102 similarly includes atransceiver 126. The transceivers 124, 126 communicate information fromthe valve 110 to the implantable medical device 102 such as for use bythe implantable device 102 to apply and change, for instance, pacingand/or defibrillation therapy. In another example, the transceivers 124,126 communicate an alert to the external system 106 (FIGS. 1A, B).Optionally, the transceivers 124, 126 use electromagnetic transmissions(e.g., RF) to communicate. In other examples, the transceivers 124, 126use ultrasound, inductive coupling, optical transmission (e.g.,infrared), electric field, the body as an electrical, optical oracoustic conductor or the like to communicate. In yet another example,the heart valves 110 shown in the aorta 120 and the pulmonary artery 122are coupled to the implantable medical device 102 with a lead systemsimilar to the lead system 104, described above. In still anotherexample, the heart valves 110 shown in FIGS. 1A, B are wirelesslycoupled with the implantable medical device 102, as described above. Inan additional example, the heart 111 includes two or more implantableheart valves 110 (e.g., tricuspid and mitral, pulmonic and aortic,combinations of the same or the like).

FIG. 2 shows one example of the cardiac management system 100 includingthe implantable medical device 102 and the heart valve 110. As shown,the heart valve 110 includes a power source 200 and at least one sensor202, such as an intrinsic cardiac sensor, hemodynamic parameter sensoror the like. In another example, the heart valve includes at least oneelectrode 204 adapted to provide sensing of intrinsic electrical cardiacor other parameters and/or therapy to the heart 111 (FIGS. 1A-D), suchas pacing and/or defibrillation therapy. The electrode 204 is optionallyconstructed with, but not limited to, bio-compatible materials such asplatinum, iridium, or the like. In yet another example, the heart valve110 includes a signal processing circuit, for instance, a pre-amplifier206 adapted to amplify the sensor measurements prior to transmitting themeasurements to the implantable medical device 102. Optionally, thesignal processing circuit includes an amplifier, filter,analog-to-digital converter and the like. The heart valve 110 includes,in still another example, a signal communications interface 208. Thesignal communications interface includes 208, but is not limited to atransceiver (such as the transceiver 124, described above), a socket forcoupling with a lead assembly (such as the lead assembly 104, alsodescribed above) or the like, and facilitates communication ofinstructions and data between the heart valve 110 and the implantablemedical device 102 along a communications link 209. The communicationslink 209 represents a flow of data (e.g., measurements, instructions orthe like) between the heart valve 110 and the implantable medical device102. For instance, the communications link 209 is at least one of awired, wireless, optical, electromagnetic field coupling or the likebetween the devices that permits communication.

The implantable medical device 102 generally includes processor module210 and a storage module 212. In one example, the implantable medicaldevice 102 receives information from the heart valve 102 at a secondsignal communications interface 214. Similar to the signalcommunications interface 208, the second signal communications interface214 of the device 102 includes, but is not limited to a transceiver, asocket for the lead assembly 104 or the like. Optionally, theimplantable medical device 102 includes an amplifier 216 or other signalprocessing circuit coupled between the signal communications interface208, the processor module 210 and the storage module 212. As shown inFIG. 2, the processor module 210 includes, in another example, acomparator module 218 and a therapy module 220. One or more of theprocessor module 210 (i.e., the module 210 generally or at least one ofthe therapy module 220, the comparator module 218 and the like) and thestorage module 212 are coupled with a transceiver 222, in still anotherexample. The transceiver facilitates communication with one or moreexternal devices, such as external system 106.

In operation, the sensor 202 of the heart valve 110 measures at leastone physiological parameter such as intrinsic cardiac electricalactivity, one or more hemodynamic parameters, chemical composition ofthe blood, temperature, valve patency, valve functionality or the like.Optionally, the valve 110 includes multiple sensors 202, as describedbelow, such as for measuring multiple physiological parameters. Themeasurement of the physiological parameter is sent through the signalprocessing circuit including the amplifier 206, in one example, andpassed on to the signal communications interface 208. The signalcommunications interface 208, as described above, transmits themeasurement (for instance, wirelessly, by the lead assembly 104 or thelike) to the second signal communications interface 214 in theimplantable medical device 102. In another example, the measurement isamplified by the amplifier 216 and sent to at least one of the storagemodule 212 and the comparator module 218. The measurement is comparedagainst a specified threshold in the module 218, in yet another example.In one option, an alert is sent to the therapy module 220, for instance,if the measurement is above the specified threshold. In another option,an alert is sent to the therapy module 220 if the measurement is belowthe specified threshold. In still another example, the therapy module220 sends a signal to the heart valve 110 and, in response, at least oneelectrode 204 at the valve 110 provides therapy (e.g., pacing,defibrillation or the like) to the heart 111 (FIGS. 1A-D). In yetanother example, the therapy module 220 sends a signal to a separatelead assembly with pacing and/or defibrillation electrodes to providetherapy to the heart 111. In a further example, the therapy module 220sends a signal to control dispensing of a drug into the patientaccording to the physiological parameter measurement. Where themeasurement does not trigger the comparator module 218, optionally, aninstruction is sent back to the heart valve 110 requesting anothermeasurement. In another option, the heart valve 110 automaticallymeasures the physiological parameter (e.g., at an interval, according toinstructions from the implantable medical device, or the like).

In another example, the measurements retained in the storage module 212are available through the transmitter 222 for use by, for instance, theexternal system 106 (FIGS. 1A, B). Similarly, in yet another example,the therapy module 220 is coupled with the transmitter 222, andoptionally transmits to the external system 106 any therapy instructionssent to the heart valve 110.

FIG. 3 shows another example of the heart valve 301 including a sensor300 for measuring at least one hemodynamic parameter, such as valvedeflection, rate of change of valve deflection, blood velocity, bloodflow, duration of valve opening or the like. Such parameters provideinformation about cardiac output, ejection fraction, contractility orthe like and assist in indicating the onset of an event (e.g.,tachycardia, defibrillation or the like) or change of an existingcondition. As shown in FIG. 3, the sensor 300 is coupled between a strut302 and a valve ring 304 of the heart valve 301. In one example, thesensor 300 includes, but is not limited to a strain gauge,piezo-electric element, piezo-resistive element or the like. A valveleaflet 306 is coupled with the strut 302 and rotates at least a portionof the strut 302 during opening and closing of the heart valve 301. Asthe valve leaflet 306 opens and closes the sensor 300 is deflected. Inanother example, the deflection is measured, such as to obtain the peakangle of the valve leaflet 306 relative to the valve ring 304. Themeasurement of the valve leaflet 306 peak angle provides an indicationof the efficiency of the heart contraction (i.e., the greater the peakangle the stronger the contraction), and is useful in determiningappropriate pacing or other therapy by the implantable medical device102, such as in a closed-loop system in which the therapy is controlledso as to maximize the measured peak angle. In yet another example, theangle measurement of the valve leaflet 306 is useful in determining theappropriate type or amount of drug to dispense by the implantablemedical device 102.

In another example, the measurement of the valve leaflet 306 peak angleis performed over time. In still another example, one or moremathematical functions, such as derivatives, integrals, approximationsof the same or the like are performed on the function of the valveleaflet 306 angle with respect to time. Optionally, integrating thevalve leaflet angle with respect to time over a cardiac cycle providesan indication of the volume of blood flow through the valve ring 304,because the ring 304 has a consistent size and shape. In yet anotherexample, blood flow volume is another measurement used in determiningthe onset of an event, changing of a condition or the like, either inaddition to or in place of peak angle of the leaflet. Where the peakangle of the valve deflection does not meet a specified threshold, asdescribed above in FIG. 2, therapy is provided (e.g., by the therapymodule 220), in one example. Optionally, the heart valve 301 includesone or more electrodes 308 adapted to provide at least one of pacing anddefibrillation therapy to the heart 111 (FIGS. 1A-D). For instance, theelectrodes 308 extend around at least a portion of the heart valve 310to provide defibrillation therapy. In another example, the electrodes308 are adapted to sense one or more intrinsic cardiac signals, such asfor use by the implantable medical device 102 for at least one ofpacing, defibrillation, resynchronization, dispensing of drugs or thelike. The heart valve 301 provides a compact device that consolidatesthe function of the replacement heart valve 301 with at least one of oneor more sensors (e.g., sensors 300, electrodes 308 or the like) forhemodynamic parameters and/or intrinsic cardiac signals and one or moreelectrodes for providing therapy as described above. Additionally, theheart valve 301 (including any integral sensors 300, electrodes 308 orthe like) is implantable in the heart 111 (FIGS. 1A-D) in a singleprocedure and eliminates the need for multiple procedures to install aheart valve, separate lead system or the like. Further, in yet anotherexample, the heart valve 301 is installed in the left side of the heart.Where the heart valve 301 includes one or more electrodes 308 forsensing intrinsic cardiac signals, installing the valve 301 in the heart111 avoids difficult navigation of the coronary sinus vasculature nearthe left side of the heart 111 required with most lead systems, andovercomes the difficulty of introducing a chronic electrode directlyinto the left side heart chambers of existing chronic intravascular leadsystems.

FIGS. 4A, B show other examples of heart valves 400A, B. The heart valve400A includes a valve ring 402, and a valve leaflet 404 rotatablycoupled with the valve ring 402 by a strut 406. As shown in FIG. 4A, thevalve ring 402 includes at least one coil 408 therein extending throughat least a portion of the ring 402. The valve leaflet 404 is magnetized(See FIG. 4A showing North and South poles). Movement of the magnetizedvalve leaflet 404 with respect to the coil 408 produces a measurablepotential across the coil 408. The potential corresponds with the fluxvariation subsequent to the change in angle and rate of change in theangle of the valve leaflet 404 with respect to the valve ring 402. Asdescribed above, the measurement of the valve leaflet 404 peak angleprovides an indication of the efficiency of the heart contraction (i.e.,the greater the angle the stronger the contraction), and is useful indetermining appropriate electrical or other therapy by the implantablemedical device 102 (FIGS. 1A-D). Additionally, the valve leaflet angleis measurable over time to obtain information about volume of bloodflow, as previously described.

Referring now to the heart valve 400B shown in FIG. 4B, the magnetizedvalve leaflet 404 and a conductive film 410 extending through a portionof the valve ring 402 or the like are used as a Hall Effect sensor tomeasure the angle of the valve leaflet 404. The conductive film 410 isin a closed circuit 412 with current flowing through the film 410.Changes in the current flow through the conductive film 410 occur as themagnetized leaflet 404 moves with respect to the valve ring 402. Thechanges in current flow are measured and correspond with the angle ofthe valve leaflet 404. In a similar manner to the heart valve sensorshown in FIG. 4A, the Hall Effect sensor shown in FIG. 4B providesinformation used to determine appropriate electrical, drug or othertherapy from the implantable medical device 102.

Referring now to FIG. 5, a heart valve 500 is shown including at leastone sensor 502 in a valve ring 504, such as for measuring a hemodynamicparameter (e.g., blood flow velocity). The valve leaflet 506 is shown ina partially open position. In one example, the sensor 502 includes anultrasound generator and ultrasound detector (for instance, apiezo-electric element) that transmits ultrasonic pulses into blood flowand measures the characteristics of the pulse, such as Doppler Shift, asthe ultrasound pulse reflects off the blood cells in the flow. Inanother example, the heart valve 500 includes a plurality of sensors 502located around the valve ring 504. At least some of the sensors 502 actas ultrasound generators and the other sensors 502 act as ultrasounddetectors. For instance, a first sensor 502 produces ultrasonic pulses,such as by applying electrical energy to a piezo-electric transducer. Asecond sensor 502 receives the ultrasound pulses after having reflectedoff of cells in the blood flow. The Doppler Shift of the pulse ismeasured by the valve 500 or the implantable medical device 102 andcorresponds with the velocity of the blood flow. As described above, asingle sensor 502 may perform both functions, in yet another example. Instill another example, the sensors 502 include optical sensors (e.g.,infrared sensors) that use light in a similar manner to ultrasound tomeasure the velocity of the blood flow. In yet another example, thesensors 502, including optical sensors, measure deflection of the valveleaflet 506 by monitoring light leakage from an optical fiber used inthe sensor 502 as the valve leaflet interposes itself between the fiberand another sensor 502. In a further example, the sensors 502 includeacoustic sensors that measure the acoustical scattering of sound fromthe valve leaflet 506 in various positions.

In another example, because the valve ring 504 has a substantiallyconsistent orifice 508 area, measuring the velocity of blood flowthrough the heart valve 500 provides information used to generate thevolume of blood flow through the valve. See, for instance, the flow rateequation below, where Q is the flow rate, V is the measured velocity andA is the area of the orifice 508.

Q=V·A

Such information (velocity, flow rate, change in flow rate or the like)can be used by the implantable medical device 102 (FIGS. 1A-D) to assistin discriminating between fibrillation and tachycardia events in theheart 111. For instance, little or no blood velocity or volume indicatesa fibrillation event. Higher blood velocity or volume indicates normalheart rhythm or tachycardia, as further described below.

FIG. 6A shows another example of a heart valve 600 having a sensor 602for measuring velocity and/or flow rate of a fluid, such as blood. Inthis example, the sensor 602 is positioned along the strut 604 andthereby in the center of the fluid flow path. The valve leaflet 606 isshown in a substantially open position. As described above, the sensor602 includes, but is not limited to, one or more ultrasonic or opticalinstruments for measuring fluid velocity. The sensor 602 measures thefluid velocity by sending and receiving pulses of ultrasound or lightthat are reflected off of blood cells and experience a Doppler shift. Inanother example, multiple sensors 602 are positioned along the strut604, and cooperate as described above with the sensors 502 shown in FIG.5 to measure fluid velocity or flow rate. In yet another example, thesensor 602 is configured to measure transit time of a fluid, such asblood flow, with ultrasonic pulses sent against the blood flow and withthe blood flow. The difference in travel time is measured and thevelocity and/or flow rate is derived from that measurement.

Referring now to FIG. 6B, a cross section of the heart valve 600 takenalong line 6B-6B is shown in an installed position within the heart 111.As shown, the sensor 602 is substantially pointing against the flowdistribution 608. In another example, the sensor 602 is pointed in adirection with the flow distribution 608. The flow distribution 608generally includes a laminar flow portion 610 extending over a largemajority of the distribution and a turbulent flow portion 612 near theedges of the distribution (e.g., along the sidewalls 614 adjacent thevalve 600). The laminar flow portion 610 generally has the highestvelocities of the fluid flow (shown by the relative height of thearrows) because the laminar flow is remote from the sidewalls 614. Thesmaller turbulent flow portion 612 generally has lower velocity becauseof the drag imparted to the fluid by the sidewalls 614. Because thesensor 602 is positioned along the strut 604, the sensor 602 is able tomake accurate readings of fluid velocity by measuring the velocity ofthe laminar portion 610 of the distribution 608. Sensors pointing intoor out of the turbulent flow portion 612 can be affected by therelatively lower velocities of the turbulent flow portion 612 andthereby provide readings that are lower than the actual velocity of themajority of the fluid flow (e.g., laminar flow portion 610).Additionally, the sensor 602 is aligned with the fluid flow path (e.g.,parallel) and thereby no adjustments are needed in calculating the fluidvelocity because of relative angles between the fluid flow and thesensor orientation.

FIG. 7 shows yet another example of a heart valve 700 including at leastone sensor 702, a valve ring 704, a strut 706 and a valve leaflet 708coupled with the strut 706 and rotatably coupled with the valve ring704. The sensor 702 includes a pressure transducer adapted to measurepressure in a chamber or vessel of the heart 111 (FIGS. 1A-D). As shownin FIG. 7, the heart valve 700 includes two pressure sensors 702positioned on either side of a parting line 710. In one example, theparting line 710 is a valve leaflet seat that receives the valve leaflet708 when the leaflet 708 is in a closed position. In another example,the sensors 702 include, but are not limited to, one or more pressuresensing diaphragms, piezo-electric elements, piezo-resistive elements orthe like. The sensors 702, in yet another example, are adapted tomeasure the pressure in a fluid flow (e.g., blood flow). In stillanother example, the sensors 702 measure the pressures in two chambersof the heart. For instance, when the valve leaflet 708 is closed, thepressure sensor 702 above the parting line 710 measures the pressure inone of the right atrium and the left atrium, and the pressure sensor 702below the parting line 710 measures the pressure in one of the rightventricle and the left ventricle, respectively (See FIGS. 1A, B).Optionally, the sensors 702 measure pressures in a chamber of the heart(e.g., the right or left ventricle), and a vessel, such as the pulmonaryartery or the aorta, as shown in FIGS. 1C, D.

As described below, pressure measurements can be used to assist indetecting an event (e.g., bradycardia, tachycardia, fibrillation or thelike). The heart valve 700 consolidates the pressure sensors 702 withthe valve 700. This provides a convenient chronic intracardiac pressuremeasurement without requiring a separate implanted chronic intracardiacpressure sensor. Pressure readings of the otherwise difficult to reachleft side are easily obtained by the heart valve 700 and relayed to theimplantable medical device 102, such as for use in providing pacingtherapy, resynchronization therapy, defibrillation therapy, drugdispensing therapy or the like.

FIG. 8 is still another example of a heart valve 800 including atemperature sensor 802 positioned within a valve ring 804. Thetemperature sensor 802, in one example, includes, but is not limited to,a thermocouple having reference nodes 806A electrically coupled withmeasurement nodes 806B in a closed circuit. The references nodes 806Aare positioned adjacent to an exterior 808 of the valve ring 804. Themeasurement nodes 806B are positioned adjacent to an interior 810 of thevalve ring 804, and are adapted to measure the temperature of a fluidflow (e.g., blood flow) through the valve orifice 812. The referencenodes 806A, in another example, use the body temperature (e.g., 98.6degrees Fahrenheit) as the reference temperature. Any difference betweenthe temperature of the fluid flow and the reference temperature isconverted into a proportional electrical signal in the circuit definedby the reference and measurement nodes 806A, B. This signal is measuredand used to determine a temperature of the fluid flow. In yet anotherexample, the measurement nodes 806B are positioned along a strut 814,and otherwise similarly coupled with the references nodes 806A, asdescribed above. In an additional example, the temperature sensor 802includes a thermistor, and the change in potential across the resistordue to temperature is measured and converted into a temperature of thefluid flow. Temperature measurements of the fluid flow are useful forassessing cardiac efficiency or condition. In one example, changes intemperature are used in assessing cardiac pacing effectiveness as wellas predicting cardiac decompensation events. Cardiac pacing parametersare automatically modulated according to temperature measurements tooptimize cardiac efficiency, in another example, as a feedbackmechanism. Temperature is used in assessing inflammation or infectionswithin the heart, in still another example. For instance, medical staffis alerted to abnormal changes in temperature resulting in medicaltherapy (e.g., medication, further examination or the like).

In another example, the thermal output of the heart is estimated usingsensors placed to observe the difference between the blood inflow andoutflow temperatures. The sensors include, for instance, thermistors,thermocouples, semiconductor junctions or similar devices. The sensedlocations include, but are not limited to, right atrium, rightventricle, left atrium, left ventricle, aortic valve, aortic outflowtract, mitral valve, tricuspid valve, pulmonic valve, coronary sinus,coronary veins or similar anatomic locations adjacent or containingblood flow with intimate contact to the myocardium. In one example, thesensors are located in one or more heart valves, as described herein.One arrangement for observing cardiac thermal output includes adifferential temperature measurement taken from the aortic valve and thecoronary sinus locations. This flow is in intimate contact with themyocardium and has sufficient transit time to communicate the heat fromthe tissue to the blood. The power dissipated as heat is proportional tothe coronary blood flow multiplied by the difference of coronary sinusand aortic outflow temperatures. In one example, at least one of anestimate of the coronary blood flow or measurements from a flow sensor(e.g., as described herein) are used in the calculation.

The efficiency of the heart is proportional to the mean pressure of theaortic outflow tract multiplied by the cardiac output all divided by thepower dissipated as heat in the muscle. The pressure of the outflow ismeasured, in another example, with pressure sensors included in theheart valve, as shown for instance, in FIG. 7. Multiple correctionfactors are included in the calculations, in yet another example, forthe refinement of this measurement. The cooling effect of bloodreturning from the pulmonary veins is optionally included in the heatcalculation if sensors are positioned in the left atrium or on or nearthe mitral valve. The temperature difference between right and leftheart inflow and outflow streams is included in the heat calculationusing the total cardiac output for net heat flux and the result used fora correction factor, in still another example. The work done on thepulmonary circuit is substantially less than that on the systemiccircuit. A pressure sensor in the pulmonic outflow tract provides theneeded information to calculate the pulmonic work and the result is usedto increase the accuracy of the system.

In still another example, a system of sensors for estimating cardiacefficiency measures the heat transferred to the primary right or leftheart flows, for instance, with heart valves including sensors tomeasure temperature in the right and left sides of the heart (describedabove). This system is implemented with a minimum of sensors whileproviding an estimation of cardiac efficiency based solely on heattransfer measurements.

Referring now to FIG. 9, another example of a heart valve 900 is shownincluding a chemical sensor 902. Examples of chemical sensors aredescribed in co-pending applications, such as Kane et al. U.S. patentapplication Ser. No. 11/383,933 entitled Implantable Medical Device withChemical Sensor and Related Methods, and Kane et al. U.S. patentapplication Ser. No. 11/383,926 entitled Implantable Medical Device withChemical Sensor and Related Methods, both of which are incorporatedherein by reference in their entirety, including their description ofchemical sensors. As shown, the chemical sensor 902 is coupled along thevalve ring 904. In yet another example, the chemical sensor 902 iscoupled along at least one of the strut 906 and the valve leaflet 908.The chemical sensor 902 is adapted to measure at least one of thefollowing, including, but not limited to, potassium, oxygen, pH,creatinine, brain natriuretic peptide (BNP), lactic acid, nitric oxideor the like. At least one of these chemicals is measured and used by theimplantable medical device 102 (FIGS. 1A-D), such as to develop pacing,resynchronization, defibrillation or drug dispensing therapies. Dataregarding chemicals used for therapy or for diagnostic purposes may bedetected by sensor 902 and provided to the implantable medical device102 storage module 212 (FIG. 2), such as for later use by a physician,for instance through the external system 106 (FIG. 1A, B).

In one example, the chemical sensor 902 includes, but is not limited toan optical light emitting and detecting sensor that measures ion and/oranalyte concentrations in a fluid flow (e.g., blood flow) to determinethe presence and concentration of particular chemicals. The chemicalsensor 902 includes a sensing element 910 adapted to translate analyteconcentrations into variable color responses in one or more chromophorematerials. The sensor 902 also includes an optical excitation module 912integrated with the sensing element 910. The excitation module 912 isadapted to illuminate the sensing element 910 and produce an opticalreturn signal that is responsive to analyte concentration. The sensor902 also includes an optical detection module 914 integrated with thesensing element 910. The detection module 914 is adapted to monitor theintensity of the optical return signal to determine analyteconcentration in interstitial fluid or plasma.

The sensing element 910 includes a fluorescent indicator and the opticalreturn signal includes an analyte dependent fluorescent return signal,in some examples. According to various examples, the sensing element 910includes a colorimetric indicator and the optical return signal includesan analyte dependent reflectance signal. In one example, the detectionmodule 914 includes a charge-coupled device (CCD) detector. Thedetection module 914 includes a photodiode detector, in another example.

The excitation module 912 includes a light-emitting diode (LED) in oneexample. The excitation module 912 includes one or more LEDs coupledwith one or more bandpass filters, each of the LED-filter combinationsemitting at a different center frequency, in another example. Accordingto yet another example, the LEDs operate at differentcenter-frequencies, sequentially turning on and off during ameasurement, illuminating the sensing element 914. As multiple differentcenter-frequency measurements are made sequentially, a single unfiltereddetector can be used. Another implementation may use one or more laserdiodes tuned to different wavelengths as illumination sources.

Another example of the chemical sensor 902 includes a reflectance-basedor transmittance-based chemical sensing system. According to thereflectance-based example, the detection module 914 is on the same sideof the sensing element as the excitation module 912, and the detectionmodule 914 is adapted to monitor the intensity of the excitation lightdiffusely reflected off of the chemical sensor 902 or fluorescent returnfrom the chemical sensor 902 to determine chemical analyteconcentration. According to the transmittance-based example, thedetection module 914 is opposite from the excitation module 912, and thedetection module 914 is adapted to monitor the intensity of theexcitation light transmitted from the excitation module 912 to determinechemical analyte concentration. Sensing may be directed at a specificion or a plurality of different ions. Examples of ions that can besensed include, but are not limited to potassium, sodium, chloride,calcium, pH and hydronium. In addition, embodiments include integratedsensors adapted to sense not only concentrations of ions, but otheranalytes of interest such as glucose, creatinine, lactate, urea, brainnatriuretic peptide (BNP), nitric-oxide and cardiac-specific troponin,for example. Sensor embodiments may be adapted to sense an ion, multipleions, an analyte of interest, multiple analytes of interest, or acombination thereof. According to other examples, the chemical sensor902 includes a sensor selected from the group consisting of anelectro-chemical sensor, colorimetric sensor, a fluorescent sensor and anear-infrared sensor.

FIG. 10A shows another example of a heart valve 1000A including a sensor1002 having first and second contacts 1004A, B that indicate whether thevalve leaflet 1006 is in an open or closed position. As shown, the firstcontact 1004A is located within a portion of the valve leaflet 1006 andis positioned to engage the second contact 1004B, in the valve ring1008, when the leaflet 1006 is in the closed position. The first andsecond contacts 1004A, B are electrically coupled by a conductor 1010extending through a portion of the valve leaflet 1006. When the valveleaflet 1006 is in the closed position a closed circuit is formed. Thesensor 1002 includes a node 1012, and in one example, the node 1012transmits the status of the valve leaflet 1006 to the implantablemedical device 102 (FIGS. 1A-D). As described above, the implantablemedical device 102 includes a storage module 212 that retainsinformation about the opening and closing of the heart valve 1000A, inanother example. In yet another example, the implantable medical device102 records the time spans the heart valve 1000A is open and closed, anduses the information for modulating a therapy, such as pacing,resynchronization, defibrillation, drug dispensing or the like.

FIG. 10B shows another example of a heart valve 1000B including sensors1002 that indicate whether the valve leaflets 1006A, B are in an open orclosed position. The heart valve 1000B is similar in at least somerespects to the heart valve 1000A, described above. For instance, eachleaflet 1006A, B includes a first contact 1004A, and the first contactis positioned to engage a corresponding second contact 1004B, in thevalve ring 1008, when the leaflet 1006A, B is in the closed position.The first and second contacts 1004A, B are electrically coupled byconductors 1010 extending through portions of the valve leaflets 1006A,B. When the valve leaflets 1006A, B are in the closed position closedcircuits are formed. The sensor 1002 includes a node 1012, and in oneexample, the node 1012 transmits the status of the valve leaflets 1006A,B to the implantable medical device 102 (FIGS. 1A-D). Providing contacts1004A, B on both of the leaflets 1006A, B allows for status monitoringof both leaflets 1006A, B (e.g., opening, closing, failure of a leafletor the like) Optionally, a single set of contacts 1004A, B are providedon one of the leaflets 1006A, B. In still another option, physicalcontacts are avoided by using low current resistive sensing, capacitivesensing, optical sensing, Hall Effect sensing devices or the like toobtain the valve leaflet position without touching metal components.Additionally, any of the sensors described herein are usable with theheart valve 1000B having double leaflets 1006A, B, or a heart valvehaving a plurality of leaflets (e.g., two or more leaflets). Further,while most of the Figures have been drawn with circular valve leafletsfor ease of understanding, the principles and techniques describedherein apply to other moving valve configurations such as the commonbi-leaflet semi-lunar designs popularly employed by physicians. Theseprinciples can be adapted to valves constructed from tissue sources suchas bovine, porcine, or homologous tissue donors. Similarly, theseprinciples can be applied to hybrid designs that use combinations ofconstruction materials and techniques.

FIG. 11 is a schematic diagram showing one example of a heart valve 1100and circuit diagram for the same. As shown, the heart valve 1100includes a magnetized heart valve leaflet 1102 having north and southpoles. The heart valve ring includes an electromagnetic coil 1104coupled with a rectifier 1106. A similar example is shown in FIG. 4.Movement of the heart valve 1100, for instance during each opening andclosing action for a heart beat creates a current in the electromagneticcoil 1104. The current passes through the rectifier 1106 and is retainedin a storage medium, such as a capacitor 1108. In another example, theheart valve 1100 includes a voltage regulator 1110 that controls theoutput of the coil 1104 and the leaflet 1102. Where the heart valve 1100is separated from the implantable medical device 102 (FIGS. 1A-D) themagnetized leaflet 1102 and coil 1104 cooperate to produce electricitysufficient for the valve 1100 to operate (e.g., sense at least onephysiological parameter, transmit measurements or the like). In yetanother example, the heart valve 1100 is powered by another energysource such as power source 200 (FIG. 2). For instance, the power source200 includes a battery, an induction coil coupled with a correspondingcoil in at least one of the implantable medical device 102, externalsystem 106 (FIGS. 1A, B) or the like.

Referring again to FIG. 11, a sensor 1112 measures a physiologicalparameter (e.g., hemodynamic characteristic, temperature, chemical,intrinsic cardiac signals or the like) and uses energy generated by theleaflet 1102 and coil 1104 (by pumping of the heart), in one example.The measurements of the sensor 1112 are optionally sent through apre-amplifier 1114 that is similarly powered by the energy obtainedthrough the pumping action of the heart on the valve 1100. In anotherexample, the measurements are transmitted to at least one of theimplantable medical device 102, the external system 106 or the like bythe transmitter 1116 and antennae 1118. As described above, in yetanother example, the transmitter 1116 operates through energy obtainedby the valve leaflet 1102 and the coil 1104. Optionally, the transmitter1116 and antenna 1118 include, but are not limited to electrodes, suchas the electrodes 308 described above (e.g., pacing and/ordefibrillation electrodes). In another option, the transmitter 1116includes transducers (e.g., sensors 502, 602 or the like) adapted tosense one or more hemodynamic or other parameters and transmitultrasound signals with such information to the implantable medicaldevice 102 (FIGS. 1A-D).

The heart valve 1100, in another example, senses for the physiologicalparameter, transmits the measurement or the like intermittently asenough energy is obtained by the storage element (e.g., capacitor 1108).For instance, when the capacitor 1108 discharges (after storing aspecified amount of energy) the sensor 1112 measures the physiologicalparameter, the measurement is amplified and then transmitted. In yetanother example, the heart valve 1100 collects a plurality ofmeasurements and stores the measurements until enough energy is retainedin the capacitor to transmit the measurements. Optionally, the heartvalve 1100 includes a microprocessor that controls the function of atleast one of the sensor 1112, transmitter 1116 or the like.

Referring now to FIG. 3, in one example, the sensors 300 coupled betweenthe valve leaflet 306 and the valve ring 304 include one or morepiezo-electric elements. Movement of the valve leaflet 306 causescorresponding deflection of the piezo-electric elements to obtainelectricity. In a similar manner described above, the piezo-electricsensor elements provide power for sensing, amplifying and transmittingsignals to at least one of the implantable medical device 102, externalsystem or the like.

FIG. 12 is an example of a flow chart showing one example of a cardiacmanagement method 1200. At 1202, a physiological parameter (e.g.,hemodynamic characteristic, temperature, chemical, intrinsic cardiacsignal or the like) is measured using a physiological sensor located atan implantable heart valve, such as one or more of including the heartvalves shown in FIGS. 1A-11. At 1204, information about thephysiological parameter, such as a measurement, is communicated from thesensor in the heart valve, such as to an implantable electronics unit,for instance, the implantable medical device 102. The information isused as a control input to control delivery of electrical or othertherapy, in one example. In another example, the information is used asa control input to control delivery of pacing therapy, resynchronizationtherapy, defibrillation therapy or drug dispensation. Optionally, theimplantable electronics unit is physically separated from the heartvalve and remote therefrom. At 1206, the method 1200 includes deliveringthe electrical therapy. For example, the electrical therapy is deliveredthrough electrodes, such as electrodes 308 (FIG. 3) in the heart valve.In yet another example, the therapy is delivered through leads separatefrom the heart valve. Delivery of the therapy is regulated by thephysiological parameter information transmitted from the heart valve tothe implantable medical device.

Several variations for the method 1200 follow. In one example, measuringthe physiological parameter includes measuring an intrinsic electricalcardiac signal (e.g., P-wave, T-wave, S-T segment, QRS-complex or thelike), the relationship between subsequent or successive ECG signals,such as morphology and intervals, or the like. Additionally, intervals,morphology or the like between individual intrinsic electrical cardiacsignal features (e.g., P-wave, T-wave, S-T segment, QRS-complex or thelike) are measured, optionally. In another example, measuring thephysiologic parameter includes measuring at least one hemodynamicparameter, such as blood flow, blood pressure, heart valve deflection,heart valve deflection rate or the like. Measuring the heart valvedeflection includes measuring the valve leaflet angle, in yet anotherexample.

In another example, the method 1200 includes detecting an event, such astachyarrhythmia, bradyarrhythmia and the like (e.g., by measuring theintrinsic electrical cardiac signal and measuring at least onehemodynamic parameter). The event is classified as a firsttachyarrhythmia type if the measured hemodynamic parameter indicatesinadequate cardiac output. The event is classified as a secondtachyarrhythmia type if the measured hemodynamic parameter indicatesadequate cardiac output. In yet another example, measuring thehemodynamic parameter indicates whether blood continues to adequatelyflow through the heart, or if the tachyarrhythmia is serious enoughthere is inadequate blood flow. In still another example, a firstanti-tachyarrhythmia therapy (e.g., anti-tachyarrhythmia pacing therapy)is delivered in response to a detected tachyarrhythmia of the firsttachyarrhythmia type. A second anti-tachyarrhythmia therapy (e.g.,defibrillation therapy) is delivered in response to a detectedtachyarrhythmia of the second tachyarrhythmia type. Additional accuracyis provided by comparing the intrinsic electrical cardiac measurementand the hemodynamic measurement with respective thresholds. Forinstance, inappropriate therapy, such as defibrillation shocking, isavoided when the hemodynamic measurement (e.g., blood flow, bloodvelocity, pressure or the like) exceeds the threshold indicating thereis still flow through the heart, while the electrical cardiacmeasurement alone may indicate a fibrillation event. Therefore,appropriate antitachycardia pacing is provided, in another example,until the condition stabilizes or the hemodynamic parameter alsoindicates fibrillation (e.g., blood flow, velocity, pressure or the likefall below the hemodynamic threshold). Optionally, a condition, such asbradycardia is detected and treated in a similar manner (i.e., bymeasuring intrinsic electrical cardiac signals and at least onehemodynamic parameter and adjusting or providing pacing therapy). Asystem including the implantable heart valve having hemodynamic sensorsas described above, along with an implantable medical device (e.g., apulse generator) that uses the measurements of the hemodynamic sensorsalong with intrinsic electrical cardiac measurements is thereby able todiscriminate more accurately between conditions and provide the moreappropriate therapy for the particular condition.

Optionally, the method 1200 includes changing a pacing site or interelectrode timing based on the measurements of the physiologicalparameter (e.g., hemodynamic parameter, intrinsic electrical cardiacsignal or the like). For instance, different electrodes at positionsalong a lead assembly (e.g., electrodes 105 on lead assembly 104) or onthe heart valve are used to deliver therapy to various heart locationsbased on the physiological parameters measured by the heart valve.Altering the pacing site or interelectrode timing based on thesemeasurements resynchronizes the spatial nature of a heart contractionand thereby increases its output.

In yet another example, the method 1200 includes obtaining energy bymovement of a portion of the valve. The energy is optionally stored inthe heart valve. The method 1200 further includes using the energy, suchas for the measuring functions (e.g., measuring at least onephysiological parameter), communicating information, includingmeasurements, to at least one of an implantable medical device, externalsystem or the like. In one example, obtaining energy includes usingblood flow for deflecting a piezo-electric element coupled between avalve ring and a valve leaflet, as described above in FIG. 3. In anotherexample, obtaining energy includes moving a magnetic portion of thevalve with respect to a coil in a valve ring, for instance, as shown inFIG. 4.

In still another example, the method 1200 includes adjusting a delaybetween electrical pulses delivered to the same or different heartchambers using the information about the physiological parameter as acontrol input. In one example, measuring the physiological parameterincludes measuring a duration for which the heart valve is open, and thedelay is adjusted so as to generally increase the measured duration forwhich the heart valve is open. Optionally, adjusting the delay isperformed as a feedback loop with the electrical pulse therapy to adjustthe heart output. Adjusting the delay between pulses according tomeasurements of the physiological parameter taken by the heart valve isperformed to resynchronize the heart function (contraction or fillingbetween the left and right sides) and thereby optimize the performanceand output of the heart. In another example, the delay is adjusted togenerally minimize a time interval between: (1) an electrical pulsedelivered to one of the right and left ventricles; and (2) an opening ofthe heart valve. Minimizing this time interval, for instance, adjuststhe output of the ventricular contractions. In yet another example,adjusting the delay includes adjusting the atrial-ventricular delaybetween an electrical pulse delivered to an atrium and an electricalpulse delivered to the ventricle during the same cardiac cycle.Optionally, measuring the physiological parameter with the heart valveincludes measuring a delay between an opening of a first valve and anopening of a second valve (e.g., at least one hemodynamic sensor isincluded in each of two replacement heart valves).

In another example, the physiological parameter measured (e.g., bloodflow, valve leaflet deflection, leaflet deflection rate, valve openingduration, blood velocity, chemical presence and concentration,temperature or the like) are used as an indication of cardiac output(described above) and valve patency. For instance, sensors in the heartvalve measure at least one of flow and pressure through the valve duringregular heart activity and also measure regurgitation of blood (e.g.,velocity, flow, pressure or the like) through the valve if the valveleaflet fails to fully close as a chamber contracts. Leaks through thevalve are thereby identified and replacement of the valve performed ifneeded. The method 1200 further includes using the indication of cardiacoutput to establish a rate-responsive pacing upper rate limit. Pacing isthereby adjusted to provide the needed cardiac output without needlesslyraising the pacing rate without obtaining a corresponding increase incardiac output.

As described above, adjustment of the hemodynamic parameter can beaccomplished by coordinating contractions of the chambers to obtainstronger contraction. For example, by adjusting the pacing site or thedelay between electrical pulses to chambers of the heart (one or morechambers) the heart contracts in a more spatially coordinated manner toadjust at least one hemodynamic parameter, such as blood flow. In oneexample, the hemodynamic parameter is measured at implantable aortic andpulmonic valves, as shown in FIGS. 1C, D.

Optionally, the hemodynamic parameter is measured at implantable mitraland tricuspid valves (FIGS. 1A, B), such as to measure the efficiency ofdiastolic function (i.e., how efficiently the heart ventricles arefilling with blood).

In an additional example, the physiological measurements taken by theheart valve are used by at least one of the implantable electronics unit(e.g., implantable medical device 102), the external system or the likefor ischemia detection in the heart. For instance, measurement of adecreased blood flow with the heart valve sensors described above mayindicate a myocardial infarction, which can then be more quickly treatedbecause of the measured change in blood flow.

FIG. 13 is another example of a flow chart showing an example of acardiac management method 1300. At 1302, an intrinsic electrical cardiacparameter is measured (e.g., a QRS complex). In one example, theintrinsic electrical cardiac parameter is measured with one or moresensors on an implantable heart valve, such as with electrode 308described above. In another example, the intrinsic electrical cardiacparameter is measured with one or more electrodes positioned along alead or an implantable medical device (e.g., such as implantable medicaldevice 102 shown in FIGS. 1A-D). In yet another example, the intrinsicelectrical cardiac parameter is measured between an electrode at thevalve and at least one of an electrode along a lead, electrode at theimplantable medical device 102 or the like. By measuring between thevalve and another electrode new sensing vectors are generated to measureelectrical parameters across a variety of regions in the heart. Asdescribed below, optionally, pacing or defibrillation therapy is alsoprovided along at least one of these vectors or along the lead assemblyand implantable medical device 102.

At 1304, the intrinsic electrical cardiac measurement is compared withan electrical cardiac reference, such as a rate threshold, morphologytemplate or the like. At 1306, a hemodynamic parameter is measured usinga physiological sensor at the implantable heart valve, as describedabove. At 1308, the hemodynamic measurement is compared with ahemodynamic reference (e.g., blood flow, blood velocity, valve leafletangle, valve opening duration, chemical presence and concentration,temperature thresholds or the like). At 1310, the method 1300 includesdetermining whether the intrinsic electrical cardiac measurement andhemodynamic measurement are representative of a detected event (e.g.,bradycardia, tachycardia, fibrillation or the like), such as based onthe comparisons of the intrinsic electrical cardiac measurement and thehemodynamic measurement. Optionally, an alert or therapy(anti-tachycardia, defibrillation, pacing, resynchronization, drugdispensing therapies or the like) are provided according to thisdetermination. Additional accuracy is provided by comparing theintrinsic electrical cardiac measurement and the hemodynamic measurementwith respective references. For instance, inappropriate therapy, such asdefibrillation shocking, is avoided when the hemodynamic measurement(e.g., blood flow, blood velocity, pressure or the like) exceeds athreshold, indicating there is still adequate flow through the heart,even though the electrical cardiac measurement alone may indicate afibrillation event. Therefore, appropriate antitachycardia pacing isprovided, in another example, until the condition stabilizes or thehemodynamic parameter also indicates fibrillation (e.g., blood flow,velocity, pressure or the like fall below the hemodynamic threshold). Asystem including the implantable heart valve having one or morehemodynamic sensors as described above, along with an implantablemedical device (e.g., a pulse generator) that uses the measurements ofthe hemodynamic sensors along with intrinsic electrical cardiacmeasurements is thereby able to discriminate more accurately betweenconditions and provide the best response for the particular condition.

Several variations for the method 1300 follow. In one example,determining the intrinsic electrical cardiac measurement and hemodynamicmeasurement are representative of a detected event includes determiningthe detected event is a first type of tachycardia event where theintrinsic electrical cardiac measurement (e.g., depolarization rate)exceeds the electrical cardiac threshold, and the hemodynamicmeasurement is above the hemodynamic threshold. In another example,determining the intrinsic electrical cardiac measurement and hemodynamicmeasurement are representative of a detected event includes determiningthe detected event is a second type of tachycardia event (e.g.,fibrillation) where the intrinsic electrical cardiac measurement (e.g.,depolarization rate) exceeds the electrical cardiac threshold, and thehemodynamic measurement is below the hemodynamic threshold.Distinguishing between symptomatic and non-symptomatic ventriculartachycardia is important because the appropriate type of therapydelivered by the device is specific to the type of ventriculartachycardia. Patients with symptomatic ventricular tachycardia (VT)and/or ventricular fibrillation (VF) have little to no blood perfusion.In this case a defibrillation shock is appropriate therapy. Patientswith episodes of non-symptomatic VT still have adequate perfusion. Inthis case other therapies such as rapid or burst pacing can break thearrhythmia with less pain and danger to the patient. Patients withbradycardia or myocardial infarction may still have adequate perfusionunless these conditions degenerate or create secondary hemodynamicallyunstable pathologies.

In one example, low cardiac output is the result of bradycardia,myocardial infract, fibrillation or the like. Low cardiac outputresulting from bradycardia is distinguishable by the presence of a lowfrequency periodic contraction of the heart. Around 60 beats per minuteor less with low cardiac output and a distinct periodic ECG or valvesensor signal (described above) is indicative of this cause. The heartrate signal can be observed using electrodes to detect thedepolarization potentials, the valve position or valve motion sensor todetect the rate of valve cycling, the flow sensor to detect the periodicrate of blood flow, or the pressure sensors to detect the periodicvariation of pressures within a chamber or across a valve.

Low cardiac output from fibrillation is distinguished, in anotherexample, by the lack of periodicity of the ECG or by the presence ofdominant high frequency components in the ECG waveform. Valve motionsensors indicate incomplete or very rapid valve position variations.Pressure sensors indicate high rate pressure fluctuations with smallamplitudes.

In yet another example, low cardiac output from infarct is distinguishedby an elevated heart rate well above the resting rate but substantiallybelow the 185 beat per minute associated with tachycardia. The suite ofsensors described above for the detection of bradycardia andfibrillation rates will provide the data to combine with the low cardiacoutput signal. These data are then processed to indicate the infarct asthe probable cause of low cardiac output. Another distinguishingcharacteristic of infarct is the change in ECG vector behavior (e.g., anelevated S-T segment). This is uniquely identifiable with a sensorequipped valve that has multiple electrodes positioned on the annulus ofthe valve body, as described above. The morphology and vector changesfrom two or more electrodes are processed (e.g., by the implantablemedical device 102, external system 106 or the like) to identify theprobable cause as infarct.

In still another example, the tachycardia event, such as fibrillation,is distinguished from a bradycardia condition or myocardial infarct bymeasuring the R-R interval, for instance, with sensors in the heartvalve. Fibrillation has a measurably shorter R-R interval thanbradycardia or a myocardial.

In another example, the hemodynamic threshold includes a valve leafletangle threshold and measuring the hemodynamic parameter includesmeasuring a valve leaflet angle, as described above in FIGS. 3 and 4,for example. In yet another example, the hemodynamic parameter measuredwith the heart valve includes blood flow pressure, pressure within atleast one chamber, blood velocity, rate of change of valve leaflet angleor the like.

In still another example, the method 1300 includes communicating atleast one of the intrinsic electrical cardiac measurement and thehemodynamic measurement to at least one of an implantable medical device(e.g., implantable medical device 102), an external system or the like.In one example, the measurements are communicated by at least one of alead assembly, EMF generation (e.g., through electrodes on the heartvalve, described above), ultrasound (through piezo-electric andpiezo-resistive elements, also described above), RF, inductive coupling,optically (e.g., with infrared light) or the like, as described above.

FIG. 14 is an example of a flow chart showing yet another example of acardiac management method 1400. At 1402, a hemodynamic parameter ismeasured using a sensor coupled with a heart valve. Examples of sensorscoupled with the heart valve are described above and shown in FIGS.2-11. At 1404, the hemodynamic measurement is compared with acorresponding hemodynamic threshold (e.g., blood flow, blood velocity,valve leaflet angle, rate of change of valve leaflet angle, valveopening duration, chemical, temperature thresholds or the like). At1406, a delay is adjusted between electrical pulses delivered to atleast one of two chambers of the heart, a single chamber of the heart(e.g., different locations within the same chamber) or the like. Thedelay is changed based on the comparison to adjust the hemodynamicparameter. For instance, the delay between pulses is adjusted toresynchronize the spatial nature of depolarization within a chamberand/or between chambers. In another example, the sensors of the heartvalve cooperate with logic (described above) within an implantablemedical device (e.g., device 102 shown in FIGS. 1A-D) to adjust pacingor resynchronization therapy in a feedback system to adjust thehemodynamic parameter. As described above, adjustment of the hemodynamicparameter is accomplished by coordinating contractions of the chambersto increase the efficiency of the heart contraction. By adjusting thedelay between electrical pulses, the chambers of the heart contract in amore coordinated manner to adjust at least one hemodynamic parameter,such as blood flow. In one example, the hemodynamic parameter ismeasured at implantable aortic and pulmonic valves, as shown in FIGS.1C, D. Optionally, the hemodynamic parameter is measured at implantablemitral and tricuspid valves (FIGS. 1A, B), such as to measure theefficiency of diastolic function (i.e., how efficiently the heartventricles are filling with blood).

Several variations for the method 1400 follow. In one example, comparingthe hemodynamic measurement with the hemodynamic parameter and adjustingthe delay between electrical pulses is performed by an implantablemedical device (e.g., device 102 shown in FIGS. 1A-D), such as a cardiacfunction management system.

In another example, the hemodynamic parameter measured is the durationthe heart valve is open. Optionally, adjusting the delay betweenelectrical pulses to at least two heart chambers based on the comparisonof the measurement with the threshold increases the duration the heartvalve is open (e.g., increases the cardiac output through the valve). Inyet another example, adjusting the delay between electrical pulses to atleast two heart chambers includes adjusting a delay between pulses tothe left and right ventricles to minimize a delay between at least onepulse and the opening of the valve to thereby enhance, for instance,cardiac output. The valve opening and pulse substantially correspond tomore efficiently expel blood through the open valve during thecontraction. In still another example, the delay is adjusted betweenpulses to an atrium and a ventricle. In an additional example, measuringthe hemodynamic parameter includes measuring a delay between the openingof a first implantable heart valve and the opening of a secondimplantable heart valve. As described above, the method 1400 includeschanging the pacing site based on the comparison to adjust thehemodynamic parameter (e.g., blood flow, valve opening duration, valveleaflet angle or the like).

It is to be understood that the above description is intended to beillustrative, and not restrictive. For example, the above-describedembodiments (and/or aspects thereof) may be used in combination witheach other. Many other embodiments will be apparent to those of skill inthe art upon reviewing the above description. The scope of the inventionshould, therefore, be determined with reference to the appended claims,along with the full scope of equivalents to which such claims areentitled. In the appended claims, the terms “including” and “in which”are used as the plain-English equivalents of the respective terms“comprising” and “wherein.” Also, in the following claims, the terms“including” and “comprising” are open-ended, that is, a system, device,article, or process that includes elements in addition to those listedafter such a term in a claim are still deemed to fall within the scopeof that claim. Moreover, in the following claims, the terms “first,”“second,” and “third,” etc. are used merely as labels, and are notintended to impose numerical requirements on their objects.

The Abstract of the Disclosure is provided to comply with 37 C.F.R.§1.72(b), requiring an abstract that will allow the reader to quicklyascertain the nature of the technical disclosure. It is submitted withthe understanding that it will not be used to interpret or limit thescope or meaning of the claims. In addition, in the foregoing DetailedDescription, various features may be grouped together to streamline thedisclosure. This method of disclosure is not to be interpreted asreflecting an intention that the claimed embodiments require morefeatures than are expressly recited in each claim. Rather, as thefollowing claims reflect, inventive subject matter may lie in less thanall features of a single disclosed embodiment. Thus the following claimsare hereby incorporated into the Detailed Description, with each claimstanding on its own as a separate embodiment.

1. A method comprising: monitoring at least two physiological parametersusing respective physiological sensors located at an implantable heartvalve including: monitoring at the heart valve an intrinsic electricalcardiac signal with an intrinsic electrical cardiac sensor located atthe heart valve, and monitoring a hemodynamic parameter at the heartvalve with a hemodynamic sensor located at the heart valve; andidentifying a cardiac event using information about the physiologicalparameters from the physiological sensors at the heart valve, theidentifying including: detecting a cardiac event using information fromat least one of the intrinsic electrical cardiac signal monitoring orhemodynamic parameter monitoring, and classifying the cardiac eventusing information from the other of the intrinsic electrical cardiacsignal monitoring or hemodynamic parameter monitoring.
 2. The method ofclaim 1, comprising communicating information about the physiologicalparameters from the physiological sensors at the heart valve to animplantable electronics unit, wherein the implantable electronics unitperforms the identifying the cardiac event and controls delivery ofelectrical cardiac therapy in response to the classifying of the cardiacevent.
 3. The method of claim 1, wherein the cardiac event includes abradyarrhythmia event and identifying the cardiac event includes:detecting the cardiac event with the intrinsic electrical signalmonitoring at the heart valve indicating one or more of a heart rate ofless than a specified threshold value or a characteristic ECGdepolarization waveform, and classifying the cardiac event as thebradyarrhythmia event when the hemodynamic parameter monitoring at theheart valve indicates hemodynamic cardiac output below a specifiedhemodynamic cardiac output threshold.
 4. The method of claim 3, whereinmonitoring the hemodynamic parameter at the heart valve includesmeasuring one or more of a periodic rate of blood flow, periodicpressure variation within a chamber, or periodic pressure variationacross the heart valve, and the specified output threshold forclassifying the cardiac event includes one or more of a periodic bloodflow rate threshold, a periodic pressure variation threshold within achamber, or a periodic pressure variation threshold across the heartvalve.
 5. The method of claim 1, wherein the cardiac event includes afibrillation event, and identifying the cardiac event includes:detecting the cardiac event with the hemodynamic parameter at the heartvalve indicating hemodynamic cardiac output below a specified outputthreshold, and classifying the cardiac event as the fibrillation eventwhen the intrinsic electrical signal measurement at the heart valveindicates one or more of a specified ECG wave form periodicity or an ECGhigh frequency component exceeding a specified high frequency threshold.6. The method of claim 5, wherein monitoring the hemodynamic parameterat the heart valve includes measuring one or more of valve motion orpressure fluctuation, and the specified output threshold for detectingthe cardiac event includes one or more of a valve motion thresholdindicating incomplete or rapid valve position variation, or a pressurechange threshold indicating small amplitude pressure fluctuations at theheart valve relative to a regular pressure fluctuation amplitude.
 7. Themethod of claim 1, wherein the cardiac event includes an ischemia event,and identifying the cardiac event includes: detecting the cardiac eventwith the hemodynamic parameter monitoring at the heart valve indicatinghemodynamic cardiac output below a specified output threshold, andclassifying the cardiac event as the ischemia event where the intrinsicelectrical signal measurement at the heart valve indicates one or moreof a heart rate above a specified resting heart rate threshold and belowa specified tachycardia heart rate threshold, or an elevated S-T segmentabove a specified S-T segment threshold.
 8. The method of claim 1,comprising adjusting the hemodynamic parameter in response to themonitoring of the intrinsic electrical cardiac signal and monitoring ofthe hemodynamic parameter.
 9. The method of claim 8, wherein adjustingthe hemodynamic parameter includes: associating a first sequentialelectrical cardiac delay with a first hemodynamic parameter measurement,associating a second sequential electrical cardiac delay with a secondhemodynamic parameter measurement, wherein the first and secondsequential electrical cardiac delays are different and in sequence witheach other, and the second hemodynamic parameter measurement is adjustedusing the first hemodynamic parameter measurement, associating a thirdsequential electrical cardiac delay with a third hemodynamic parametermeasurement, the third hemodynamic parameter measurement is less optimalthan the second hemodynamic parameter measurement, and the thirdsequential electrical cardiac delay is different from and in sequence tothe first and second sequential electrical cardiac delays, comparing thefirst, second and third hemodynamic parameter measurements, anddetermining whether the second hemodynamic parameter measurement isoptimal, and adjusting an electrical pulse therapy delay to correspondwith the second sequential electrical cardiac delay to adjust thehemodynamic parameter.
 10. The method of claim 1, comprising determininga rate responsive pacing upper rate limit.
 11. The method of claim 10,wherein determining the rate responsive pacing upper limit includes:associating a first sequential pacing rate with a first hemodynamicparameter measurement, associating a second sequential pacing rate witha second hemodynamic parameter measurement, the first and secondsequential pacing rates are different and in sequence with each other,and the second hemodynamic parameter measurement is optimal relative tothe first hemodynamic parameter measurement, associating a thirdsequential pacing rate with a third hemodynamic parameter measurement,the third hemodynamic parameter measurement is less optimal than thesecond hemodynamic parameter measurement, and the third sequentialpacing rate is different from and in sequence to the first and secondsequential pacing rates, comparing the first, second and thirdhemodynamic parameter measurements, and determining whether the secondhemodynamic parameter measurement is optimal, and adjusting anelectrical pacing rate to correspond with the second sequential pacingrate for use as the rate responsive pacing upper limit.
 12. A methodcomprising: monitoring at least two physiological parameters usingrespective physiological sensors located at an implantable heart valveincluding: monitoring at the heart valve an intrinsic electrical cardiacsignal with an intrinsic electrical cardiac sensor located at the heartvalve, and monitoring a hemodynamic parameter at the heart valve with ahemodynamic sensor located at the heart valve; and identifying one ormore cardiac events using information about the physiological parametersfrom the physiological sensors at the heart valve, the identifyingincluding: detecting a cardiac event using information from thehemodynamic parameter monitoring at the heart valve, classifying thecardiac event as a first cardiac event using information from theintrinsic electrical cardiac signal monitoring at the heart valve thatmeets a first intrinsic electrical threshold, and classifying the eventas a second cardiac event using information from the intrinsicelectrical cardiac monitoring at the heart valve that meets a secondintrinsic electrical threshold different from the first intrinsicelectrical threshold.
 13. The method of claim 12, wherein identifyingone or more cardiac events includes: detecting the cardiac eventincluding a low hemodynamic output event with the hemodynamic parametermonitoring at the heart valve, classifying the low hemodynamic outputevent as the first cardiac event including bradyarrhythmia when theintrinsic electrical cardiac signal monitoring indicates a heart rate ofless than a specified threshold value, classifying the low hemodynamicoutput event as the second cardiac event including fibrillation if theintrinsic electrical cardiac signal monitoring indicates a specified ECGwave form periodicity or an ECG high frequency component exceeding aspecified high frequency threshold.
 14. The method of claim 12, whereinidentifying one or more cardiac events includes: detecting the cardiacevent including a low hemodynamic output event with the hemodynamicparameter monitoring at the heart valve, and classifying the lowhemodynamic output event as the first cardiac event including ischemiaif the intrinsic electrical cardiac signal monitoring indicates a heartrate above a resting heart rate threshold and below a tachyarrhythmiaheart rate threshold.
 15. The method of claim 14, wherein ischemiaincludes myocardial infarction.
 16. The method of claim 14, whereinclassifying the low hemodynamic output event as the second cardiac eventincludes classifying the second cardiac event as one of bradyarrhythmiaor tachyarrhythmia including: classifying the second cardiac event asbradyarrhythmia where the intrinsic electrical signal monitoringindicates the heart rate is below the resting heart rate threshold, andclassifying the second cardiac event as tachyarrhythmia where theintrinsic electrical signal monitoring indicates the heart rate is at orabove a tachyarrhythmia heart rate threshold.
 17. The method of claim12, wherein identifying one or more cardiac events includes: detectingthe cardiac event including a low hemodynamic output event with thehemodynamic parameter monitoring at the heart valve, and classifying thelow hemodynamic output event as the first cardiac event includingischemia when the intrinsic electrical cardiac monitoring indicates anelevated S-T segment relative to an S-T segment threshold.
 18. Themethod of claim 12, wherein identifying one or more cardiac events usinginformation about the physiological parameters from the physiologicalsensors at the heart valve includes: detecting the cardiac eventincluding a low hemodynamic output event with the hemodynamic parametermonitoring at the heart valve, and classifying the cardiac event as afirst cardiac event including bradyarrhythmia when the intrinsicelectrical cardiac monitoring indicates a distinct bradyarrhythmiaperiodic ECG signal.
 19. The method of claim 12, wherein identifying oneor more cardiac events with information about the physiologicalparameters from the physiological sensors at the heart valve includes:detecting the cardiac event including a low hemodynamic output eventusing the hemodynamic parameter monitoring at the heart valve, andclassifying the cardiac event as a first cardiac event includingfibrillation when the intrinsic electrical cardiac monitoring indicatesa specified ECG wave form periodicity threshold of an ECG wave form oran ECG high frequency component exceeding a specified high frequencythreshold.
 20. The method of claim 12, wherein monitoring thehemodynamic parameter at the heart valve includes one or more ofmonitoring a periodic rate of blood flow with a flow sensor, monitoringa valve cycling rate or monitoring pressures within one or more heartchambers.